Category Archives: GNS3

At least when I took it all you really needed was GNS3 and some books.

There are some great videos out there too. I don’t often plug pay sites (they’ve given me nothing…promise), but cbtnuggets.com has a guy named Jemery Cioara that is becoming something of a legend in the networking community. I don’t think I’ve spoken to somebody in the network world who hasn’t seen his CCNA/CCNP series done for cbtnuggets. I did, they helped a lot with some concept stuff. Don’t think that only watching the videos will give you everything you need. There’s still that pesky memorization stuff that they throw on the exams that you can only really get out of a book, but they’re a great start.
As for GNS3 all you really need to use is a 3725 router and add different switch modules (right click on the router when it’s in the topology and Configure > Slots…add serial or switch modules from there). If you get the correct image for the 3725 you can run all the protocols covered on the exams (even IS-IS and IPv6).

I liked to come up with scenarios that were a bit more real-world based. I mean, when was the last time anybody got onto a new job to find that everything was standardized and perfectly efficient? So when putting together some of the networks for redistribution exercises or switching networks for STP practice think to yourself “How would a network look if 3 different engineers had different budgets and priorities?” Then build that.

Pretend there are some old models kicking around that don’t support newer protocols (or just haven’t been upgraded in years).

Pretend that a project was started to migrate to a different IGP, but was never completed because somebody left.

I know I had a mental block when looking at some scenarios. I would think to myself “Why in the world would this ever happen?” It happens. More often than you’d like. Most of the people I talk to lately are working on projects to fix what has happened in the past…so there will be some migration plans that look dirty, but are needed because you can’t get to the whole network in one maintenance window. So, the “why” doesn’t matter anymore, just that it “has.”

It’ll dump you back to the previous screen with the line selected with an X on it. Hit the tab key and then enter.

Select 1 to install via CD or DVD and hit yes on the next screen

It’s going to do some stuff now…be patient here, don’t freak out if it doesn’t look like it’s moving for a while. You’ll see multiple progress bars and finally you’ll get to this…select yes when you get here.

Go down to set root password and hit enter…then type in a password for this image, please remember it

Go ahead and exit when you get to the next screen

Now exit the install…yes, you’re sure you want to exit.

This will restart the qemu application…hit Ctrl+Alt+2 to kill it…that’ll take you to this

Type Q and hit enter to exit. That’ll close the qemu window and take you back to your command prompt.

GNS3 is just about the best thing ever. If you’ve never used it, you should. Talk about the amazing things that people will build and publish for free.

For those who are unfamiliar with GNS3 it is a graphic network simulator (g…n…s…get it?). Basically you get to run virtual routers and switches that actually run IOS (it was primarily designed for Cisco gear). It’s not a crappy emulator where commands aren’t available and you don’t actually get to see traffic flow, it’s the real deal (well…virtually). Virtual packets get passed from device to device that you can use wireshark to sniff, you can bind physical interfaces on your computer to virtual interfaces to create even larger networks. In short, it’s awesome.

If you need to study for a CCNA or CCNP this is the most valuable tool you can have. I have a friend who has been using it to study for his CCIE, where he has run into some issues, but not many. Think about how great that is: You can download a program, for free, instead of paying thousands of dollars to build a network rack, plus saving your electricity bill and keeping your friends from thinking that you’re the ultimate geek every time they walk into your place.

That’s enough about how amazing this application is (and the kind and generous souls who have put their time into developing it). I’ll probably do some posts later about little helpful tricks I’ve found, but on to the main point of this post: Junos and GNS3.

I had a bit of trouble locating a good step by step guide to integrating a Junos Olive with GNS3. They have posts on their forums and several other people have posted guides to do this, so am I just re-posting? Kind of. My problem with a lot of the guides out there is that they were done by people who run some build of Linux or Mac (which I guess would be a Linux build now…right?).

I don’t run Linux I use Windows. I know, I know. “You call yourself a tech and use Windows?” Yes. Yes I do. I’ve tried Linux and it’s great for what it is, but it’s not what I need in a daily OS. That’s a different rant.

The best thing I was able to find when I was searching was this video on youtube (credit where credit is due). It’s pretty good and got me to where I needed to be. There are a couple of parts I modified, but for the most part it follows this video.

Time for the juicy part, the actual setup:

First thing you need to do, download all the stuff. You can use different versions, but I know these work. Please feel free to tinker and let me know others work better or not at all.

Save files wherever you like. For me I found it easiest to create an Olive directory right off the root of the C drive. As you move forward through this make sure to modify any commands with different file locations that you use.

1) If you don’t already have it go to GNS3.org and pull the full install package and install it. I’m using 0.8.3 for this guide.